Ac/Dc Current question

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Hey from AustraliaI am confussed atm between what metals i can tig with ac and dc currentFrom my understanding ac is used for welding stainless, mild steel etc and dc current is used for welding alloy etcThis is the intverter welder im currently looking athttp://www.ebay.com.au/itm/NEW-3-MUL...item20c16517d9In the description it provides, it says it can weld stainless, mild steel etc with dc current which confusses the hell out of meIf any one can help me would be awesome,
Reply:AC aluminum and magnesium.  DC all the rest.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:Generally AC is required for Aluminium.If using DC it has to be done at higher power on thicker plate.Mike
Reply:hang on i have it mixed up, thanks guys for the clarafication ill have to have a look at my inverter welder. will let you no
Reply:Thanks guys for the help, the above welder i showed you guys i bascially want for the plasma cutter function but would be nice to have a back inverter welder in case my other inverter welder at home packs it.This is the same welder i have at homehttp://www.ebay.com.au/itm/200-AMP-A...item519ef13b3aPretty decent welder, only thing  i didnt like was the gas hose setup for the tig welder on the back of itSo i waited till the warrenty ran out and atm im changing the hose set up inside of it,.Last edited by frd906; 04-22-2012 at 07:32 AM.
Reply:The plasma torch and the TIG torch both use DC negative on the torch.MMA depends on the wire used. Most stick is DC positive or AC.
Reply:GMAW on Aluminum = DCEP.  GTAW on aluminum - ACHF.  JGSMAW,GMAW,FCAW,GTAW,SAW,PAC/PAW/OFCand Shielding Gases.  There all here. :
Reply:First, I recommend you slow down a bit.  You already have bought a TIG welder but you didn't even understand what (or why) AC is typically used on Aluminum.  You would probably do yourself a big favor and look locally for a welding course - maybe community colleges, maybe vocational schools etc.  You are in for a lot of frustration if you don't.You'll find that the specs called out on that ad might be, shall we say, 'made up'.1) Its MOSFET not "mofset"2) The powerfactor seems really off.  Cos .8?   .8 Radians?  That 's like 65% (it counts towards efficiency).3) Most welders have separation between input power supply and output line.  The advert suggests that the PWM (ie MOSFET) circuit works direct on the output.  I suspect you might have some serious line noise (maybe not, just seems funny).4) The machine in the picture is DC only.  No AC.  While you might be able to do some alumimum with Helium, you probably aren't ready for that yet.  Think "frustration".5) Don't believe the duty cycle claims.  It sounds like th torch is 60% duty cycle (at whatever rated amps), I don't think the whole machine is and certainly not at 200Amps.  The good news is that MOSFETs tend to be safer when overheating (you tend to loose power rather than melt things internally).At the very minimum, I would suggest you get as much material as you can find off the Miller, Lincoln, or Esab web sites on TIG and Stick welding. If you can't find a welding course, maybe you can find a local professional that is willing to teach.  Keep in mind that material costs can add up quickly (welding schools typically are a bargain when it comes to materials alone).A key aspect of welding is safety.  Around here most welding schools won't even let you in the shop until you pass a written exam on safety.Con Fuse!Miller Dynasty 350Millermatic 350P-Spoolmatic 30AMiller Multimatic 200Hypertherm PowerMax 1000G3Miller Maxstar 200DX
Reply:I couldn't find a manual for the exact brand you listed, but I did find a manual for almost the exact same welder from another company, which isn't too surprising since a lot of the foreign design houses sell their welders to many different distributors. http://www.pinnaclewholesalers.com.a...t416manual.pdf Originally Posted by con_fuse9You'll find that the specs called out on that ad might be, shall we say, 'made up'.1) Its MOSFET not "mofset"2) The powerfactor seems really off.  Cos .8?   .8 Radians?  That 's like 65% (it counts towards efficiency).3) Most welders have separation between input power supply and output line.  The advert suggests that the PWM (ie MOSFET) circuit works direct on the output.  I suspect you might have some serious line noise (maybe not, just seems funny).4) The machine in the picture is DC only.  No AC.  While you might be able to do some alumimum with Helium, you probably aren't ready for that yet.  Think "frustration".5) Don't believe the duty cycle claims.  It sounds like th torch is 60% duty cycle (at whatever rated amps), I don't think the whole machine is and certainly not at 200Amps.  The good news is that MOSFETs tend to be safer when overheating (you tend to loose power rather than melt things internally).
Reply:Havent checck this in a bit but, ive had no issues with the welder i bought, used the stick welding side of things on a custom tray for a back of a smal truck with no problems at all and a few other things around the housse etcI start proobally this weekend using the tig side of things.Also im not sure if you read my introduction thread but i am actually a qualified boiler maker here in aussie, only reason i asked about the diff between the currents is becuase the only tiging i have done was through my tafe years and since then i havent touched a tig in a while and every one forgets things once in a while, thats why iasked on here to make sure i was right
Reply:Hi Matthew,Here is a useful PDF put out by Miller, that I found today -http://www.millerwelds.com/pdf/gtawbook.pdfMike
Reply:Thanks but i have my own tafe books from when i did my apprenticeships
Reply:Thats ok Matthew, I just like to check out as much info as I can 'coz different authors can put it a better way so that I can understand All the bestMike
Reply:Originally Posted by ZmechanicI couldn't find a manual for the exact brand you listed, but I did find a manual for almost the exact same welder from another company, which isn't too surprising since a lot of the foreign design houses sell their welders to many different distributors. http://www.pinnaclewholesalers.com.a...t416manual.pdfTo address some of those points..2). I don't know where you got 0.8 (I couldn't find it on the ad ). In any case, that's not the correct way to use the power factor. It's a dimensionless unit from 0 to 1. You are trying to use it as the phase angle between the current and voltage. A power factor of 0.8 would mean that to get 1kW, the welder would draw 1.25kVA from the line. That gives a phase angle of 36.87 degrees. Also, from the high-level schematic of the welder's manual I did find, which is most likely identical, I can see the welder has power factor correction in it, which is why they list the power factor as 0.93. Besides, if you want some nasty power factors, go get an older traditional transformer machine. Hahaha. 3). If this welder didn't have galvanic isolation of some sort, it would be a DEATH TRAP. It wouldn't be an inverter welder if I wasn't using a transformer, anyway. It rectifies the line voltage direct to DC, then switches it through a transformer at much faster frequencies than 60Hz, allowing a much smaller transformer.
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